Marisa Repasch

Assistant Professor

Photo: Marisa Repasch
Ph.D., University of Potsdam (Germany), 2021

Related Website/s

Research Area/s:

Hydrology,  Geochemistry/Petrology/Mineralogy,  Surface Processes,  Carbon Cycle,  Stable Isotope Geochemistry,  Cosmogenic Radionuclide Geochemistry

Research and Academic Interests:

My research aims to understand the role of Earth surface processes, such as erosion, sediment transport, and weathering, in the global carbon cycle. Climate change and human-driven land disturbance can accelerate erosion and modify sediment transport pathways, ultimately determining whether organic carbon is stored in the landscape or oxidized and released to the atmosphere. However, we do not have a mechanistic understanding of these changes will alter the global carbon cycle in the future. 

Overarching research questions:

  • Is climate change accelerating erosion and carbon loss from Arctic landscapes?
  • What happens to terrestrial organic carbon in the oceans?
  • How does river engineering, such as damming, impact the source to sink pathways of sediment and organic carbon?
  • Do wildfires limit or enhance the amount of organic carbon that can be stored in hillslope soils?

Answering these research questions requires an interdisciplinary approach. I use field instruments, including ADCPs and geophones, to measure modern fluxes of river water and sediment transported across the landscape. I also apply cosmogenic radionuclide geochemistry to estimate long-term catchment-average erosion rates and floodplain sediment transit times. I also use novel approaches in radiocarbon and stable isotope geochemistry to determine the reactivity of organic carbon in soil and sediment. Linking these physical and geochemical datasets allows us to better understand the impact of climate change and human-driven land disturbance on the global carbon cycle and improve models of the carbon-climate feedback.

Current field sites include the Canning River on the North Slope of Alaska, the Yukon River Delta, and the Rio Bermejo in South America, all places where erosion and sediment transport are dominant processes shaping the landscape.

Note to Prospective Graduate Students:

I will be joining the UNM EPS Department as an assistant professor of Earth Surface Processes in January 2024. I am recruiting a motivated student to join my research group starting in Fall 2024. Please reach out to me if you are a prospective student interested in pursuing a Ph.D. in the field of Earth Surface Processes. I am always excited to discuss research ideas and career trajectories with motivated students.

Through our research projects, there will be opportunities to collaborate with scientists from the USGS and Sandia National Laboratories. Our research will also take advantage of several state-of-the-art research facilities housed at UNM, including the Center for Stable Isotopes (CSI), Center for Advancement of Spatial Informatics Research & Education (ASPIRE), Electron Microbeam Facility, and Analytical Geochemistry Laboratory.

Undergraduate students interested in conducting a research project or becoming a research assistant are encouraged to reach out to me as well!

Recent Publications:

Repasch, M., Wittmann, H., Scheingross, J.S., Sachse, D., Szupiany, R., Orfeo, O., Fuchs, M. and Hovius, N., 2020. Sediment transit time and floodplain storage dynamics in alluvial rivers revealed by meteoric 10Be. Journal of Geophysical Research: Earth Surface, 125(7), p.e2019JF005419.

 Repasch, M., Scheingross, J.S., Hovius, N., Lupker, M., Wittmann, H., Haghipour, N., Gröcke, D.R., Orfeo, O., Eglinton, T.I. and Sachse, D., 2021. Fluvial organic carbon cycling regulated by sediment transit time and mineral protection. Nature Geoscience, 14(11), pp.842-848.

 Repasch, M., Scheingross, J.S., Hovius, N., Vieth‐Hillebrand, A., Mueller, C.W., Höschen, C., Szupiany, R.N. and Sachse, D., 2022. River organic carbon fluxes modulated by hydrodynamic sorting of particulate organic matter. Geophysical Research Letters, 49(3), p.e2021GL096343.

 Repasch, M., Karlstrom, K., Heizler, M. and Pecha, M., 2017. Birth and evolution of the Rio Grande fluvial system in the past 8 Ma: Progressive downward integration and the influence of tectonics, volcanism, and climate. Earth-Science Reviews, 168, pp.113-164.

 Repasch, M., 2021. Unexpected consequences of river engineering on the carbon cycle. AGU Advances, 2(1), p.e2021AV000402.

Repasch, M., Scheingross, J. S., Cook, K. L., Sachse, D., Dosch, S., Orfeo, O., & Hovius, N. (2023). Lithospheric flexure controls on geomorphology, hydrology, and river chemistry in the Andean foreland basin. AGU Advances4(5), e2023AV000924.